“In Mīmāṃsā (a philosophical system to interpret the Veda, especially the Brāhmaṇa and Mantra, with the object of correctly performing the Veda rituals) there is a word called Prayoga (connection).
The same Mantra has to be recited differently for different rituals.
Or different Mantra in the same ritual.
So even here different applications are needed, the ancients recognised this.
There is a verse which says that if the Mantra is not used correctly it has the opposite effect and destroys or boomerangs.
Instead of doing good it will harm.
This is Mithyā Prayoga (wrong connection) with an opposite effect.
Having spoken of viniyoga (appropriate application), now looking at important points the old teachers used to convey these ideas.”
– TKV Desikachar France 1983